[4287] in Athena Bugs
cleanup program for dialup
daemon@ATHENA.MIT.EDU (John Carr)
Thu Feb 22 02:34:51 1990
To: bugs@ATHENA.MIT.EDU
Date: Thu, 22 Feb 90 02:34:26 EST
From: John Carr <jfc@ATHENA.MIT.EDU>
This message contains the cleanup program that runs on the dialup servers
(there is nothing about it which requires that it be run on a dialup server;
I intend to propose that it be run on all public workstations). It should
be installed in our source tree.
/* Cleanup for dialup.
*
* Author: John Carr <jfc@athena.mit.edu>
*
* 1. Create /etc/nologin. If it exists or can't be created, fail.
*
* 2. Find logged in users. This should be the union of those users in
* /usr/adm/utmp and a file to be named later containing the list of
* background process owners (latter feature not implemented).
*
* 3. Kill processes owned by users who are not logged in.
*
* 4. Re-create /etc/passwd from user list and hesiod (since $HOME is
* inherited, this should not break anything).
*
* 5. Remove /etc/nologin
*/
#include <stdio.h>
#include <sys/file.h>
#include <sys/types.h>
#include <sys/errno.h>
#include <utmp.h>
#include <pwd.h>
#include <nlist.h>
#include <hesiod.h>
extern void make_passwd(int,uid_t *);
struct nlist nl[] =
{
#define PROC 0
{ "_proc" },
#define NPROC 1
{ "_nproc" },
{ ""}
};
static char *nologin_msg = "Try again in a few seconds...\n";
int main(int argc,char *argv[])
{
int fd, r, i, nuid;
struct utmp u;
uid_t uids[64];
fd = open("/etc/nologin", O_RDWR | O_EXCL | O_CREAT, 0775);
if(fd < 0)
if(errno == EEXIST)
{
if(getuid())
fputs("/etc/nologin exists. Failing.\n",stderr);
exit(2);
} else {
fprintf(stderr, "Can't create /etc/nologin, %s.\n", sys_errlist[errno]);
exit(3);
}
(void)write(fd, nologin_msg, strlen(nologin_msg));
(void)close(fd);
fd = open("/etc/utmp", O_RDONLY);
if(fd < 0)
{
fprintf(stderr, "Couldn't open /etc/utmp, %s.\n", sys_errlist[errno]);
exit(4);
}
uids[0] = 0; /* Don't kill off root... */
uids[1] = 1; /* ...or daemon. */
for(i=2;(r = read(fd, &u, sizeof (u))) > 0 && i < 64;i++)
{
register struct passwd *p;
char buf[9];
if(u.ut_name[0] == '\0')
{
i--;
continue;
}
bcopy(u.ut_name, buf, 8);
buf[8] = '\0';
p = getpwnam(buf);
if(p == 0)
{
fprintf(stderr, "Warning...could not get uid for user \"%s\".\n", buf);
i--;
} else {
uids[i] = p->pw_uid;
}
}
nuid = i;
while(--i>=0)
printf("uids[%d] = %d\n", i, uids[i]);
/* Now: loop through all processes, getting the uid.
* First pass: send HUP
* (sleep ...)
* Second pass: send KILL
*/
kill_uids(nuid,uids, 0, 1, 1);
sleep(2);
kill_uids(nuid,uids, 0, 0, 9);
make_passwd(nuid,uids);
if(unlink("/etc/nologin") < 0)
fprintf(stderr, "Warning: unable to unlink /etc/nologin.\n");
return 0;
}
#include <sys/time.h>
#include <sys/proc.h>
int kill_uids(int nuid,uid_t *uids,int except,int debug,int sig)
{
char *kernel = "/vmunix";
struct proc p[16];
int i,j,k,nproc,procp;
int kmem;
int self = getpid();
static int n_done = 0;
printf("nuid = %d\n", nuid);
if(n_done == 0 && nlist(kernel, nl) != 0)
{
fprintf(stderr, "Error: can't get kernel name list.\n");
exit(5);
}
n_done = 1;
if((kmem = open("/dev/kmem", O_RDONLY)) < 0)
{
fprintf(stderr, "Error: can't open kmem (%s).\n", sys_errlist[errno]);
exit(6);
}
lseek(kmem, nl[NPROC].n_value, L_SET);
read(kmem, &nproc, sizeof(nproc));
lseek(kmem, nl[PROC].n_value, L_SET);
read(kmem, &procp, sizeof(procp));
lseek(kmem, procp, L_SET);
for(i=0;i<nproc; i+=16)
{
read(kmem, &p, sizeof(p));
for(j=i;j<(i+16);j++)
{
if(j >= nproc)
goto done;
for(k=0;k<nuid;k++)
if(p[j-i].p_uid == uids[k])
goto out;
if(p[j-i].p_pid == except || p[j-i].p_pid == self)
goto out;
if(debug)
printf("killing proc %d, uid %d\n", p[j-i].p_pid, p[j-i].p_uid);
kill(p[j-i].p_pid,sig);
out:
continue;
}
putchar('.');
}
done:
(void) close(kmem);
return 0;
}
void make_passwd(int nuid,uid_t *uids)
{
int fd = open("/etc/passwd.new",O_RDWR | O_CREAT | O_TRUNC);
int proto,r,i;
char buf[1024],**ret;
if(fd == -1)
{
fprintf(stderr,"Couldn't open \"/etc/passwd.new\", %s.\n",
sys_errlist[errno]);
return;
}
if((proto = open("/etc/passwd.local", O_RDONLY)) == -1)
{
fprintf(stderr,"Couldn't open \"/etc/passwd.local\", %s.\n",
sys_errlist[errno]);
close(fd);
return;
}
while((r = read(proto,buf,1024)) > 0)
write(fd,buf,r);
if(r < 0)
{
fprintf(stderr,"Couldn't open \"/etc/passwd.local\", %s.\n",
sys_errlist[errno]);
close(fd);
close(r);
return;
}
for(i=0;i<nuid;i++)
{
char uname[8];
if(uids[i] == 0 || uids[i] == 1)
continue;
sprintf(uname,"%d",uids[i]);
ret = hes_resolve(uname,"uid");
if(ret == NULL)
{
fprintf(stderr,"Couldn't get hesinfo for uid %d, error %d.\n",
uids[i],hes_error());
} else {
if((write(fd,*ret,strlen(*ret)) < 0)/*||(write(fd,"\n",1) < 0)*/)
fprintf(stderr,"Error writing \"/etc/passwd.new\": %s.\n",
sys_errlist[errno]);
else
printf(">>>%s\n", *ret);
write(fd,"\n",1);
}
}
if(unlink("/etc/passwd") == -1)
perror("unlink");
if(rename("/etc/passwd.new", "/etc/passwd") == -1)
perror("rename");
}
